"Chicken skin" effect when scanning b/w images

Discussion in 'Digital Cameras' started by jersie0, Feb 7, 2005.

  1. jersie0

    jersie0 Guest

    I have an ancient cheap Acer scanner that works just fine for me the
    few times I need it.

    The one thing it does miserably though is scanning black and white
    photos out of books. I've tried scanning pictures from old high
    school yearbooks, or pictures out of books so my kids can use them in
    history reports, and here's what happens:

    I get an image with a pattern of dots visible all over the darker
    portions. It looks like there was a net draped over the image. Or it
    looks like the image has goosebumps. I'll call it the "chicken skin
    effect" because the evenly-spaced translucent dots look like the
    surface of skin from uncooked poultry.

    Is there some special technique I'm supposed to be using when scanning
    black and white photos (any photos maybe) from books? Mind you, my
    scanner's not great, but text comes out fine, color or black and white
    standalone photos come out great, it's only when scanning from a book
    that I get this phenomenon.

    Yes, as best I can, I press down on the scanner cover while the scan
    is occurring. I've even left the cover up and pressed down on the
    book hard enough that the page is clearly hard up against the glass.

    This one is driving me nuts. Anyone else ever see it? And what's the
    answer?
     
    jersie0, Feb 7, 2005
    #1
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  2. jersie0

    Bob Williams Guest

    You get the "dotted" scanned image because the original image is dotted.
    You are not scanning a continuous tone B/W photo. You are scanning a low
    resolution, printed image. It is composed of many fine discrete dots.
    Your scanner SHOULD have a setting for scanning images printed from
    Newspapers, Magazines, Fine Art Prints, etc.
    In your case, you should select the setting for newspapers.
    It won't "Cure" the problem but it will help a lot.
    Bob Williams
     
    Bob Williams, Feb 7, 2005
    #2
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  3. jersie0

    Ken Weitzel Guest

    Hi...

    I agree... and add that a carefully chosen degree of
    edge preserving smooth will help, too.

    Ken
     
    Ken Weitzel, Feb 8, 2005
    #3
  4. The Median filter can be useful too, but again you may need to sharpen
    your edges afterwards.

    Cheers
    Steve
     
    Bartshumandad, Feb 9, 2005
    #4
  5. jersie0

    Owamanga Guest

    Sometimes rotating the original anywhere between 5 & 45 degrees
    (experiment) on the scanner bed can help the above filters work
    better.
     
    Owamanga, Feb 9, 2005
    #5
  6. jersie0

    jersie0 Guest

    Wanted to thank everyone for the great suggestions. Yeah, the Morais
    (spelling?) issue was what I was dealing with, and all the tips here
    helped.
     
    jersie0, Feb 9, 2005
    #6
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